Here below I publish shematics and video of the working prototype of the iPhone connect-able Geiger Counter which works with iPhone (Geiger bot app)
The high voltage generator seen in the video above is on eBay - item number 161121230169
The link is http://www.ebay.com/itm/161121230169
(note transistor here is 2N3904 but any similar/popular NPN type would do either)
The whole schematics runs on 2xCR2025 3V batteries (6V). Batteries theoretically should last more than a year as theaverage power consumption is something around 10uA(10^-6A).
In the video it works with GeigerBot https://sites.google.com/site/geigerbot/
which is freely downloadable from appstore
Dimensions of the prototype board you see here are: